In recent years, a considerably increased number of patients suffer glucose metabolism disorders including obesity and Type II diabetes (hyperglycemia), mainly due to a change in dietary habits.
Generally, blood glucose level elevates after a meal, particularly after ingestion of a meal containing carbohydrate, and insulin is secreted by pancreatic β cells. Insulin acts on muscle, liver, adipose tissue, and the like and promotes the intake of sugar into cells, whereby an acute increase in blood glucose level after a meal is suppressed. However, when the postprandial blood glucose level remains high due to impaired insulin sensitivity (i.e., insulin resistance), the pancreas secrets a large amount of insulin so as to suppress an increase in blood glucose. If such a state continues for a long period of time, the pancreas is exhausted, to thereby decrease insulin secretion by pancreatic β cells. Eventually, the insulin action mechanism does not normally function, which triggers Type II diabetes or the like.
Postprandial hyperglycemia caused by insulin resistance is also observed in non-diabetes healthy people and borderline diabetes patients. In addition, postprandial hyperglycemia is known to cause obesity, hyperlipidemia, arteriosclerosis, etc. as well as Type II diabetes, and to serve as an exacerbation factor therefor. Therefore, prevention of postprandial hyperglycemia is very important from the viewpoints of health maintenance, lowering the risk for onset of these symptoms and disorders, and prevention thereof.
Under such circumstances, in recent years, there have been developed a number of substances that can suppress an acute increase in postprandial blood glucose and insulin secretion. Some of these substances are amylase inhibitors, and a wheat-originating amylase inhibitor is employed for prevention and treatment of diabetes, obesity, etc. (Non-Patent Document 1).
The endosperm of wheat contains about 10 to about 15% protein, and albumin (water-soluble protein) occupies about 11% of the protein composition. It has been reported that albumin has α-amylase inhibitory activity and physiological functions such as postprandial blood glucose increase inhibitory action and insulin resistance improving action (Non-Patent Documents 1 and 2). Above all, a wheat albumin having an electrophoretic mobility of 0.19 exhibits high α-amylase inhibitory activity, and therefore application thereof to various foods is expected.
In order to obtain physiological functions of wheat albumin, a single injection of the wheat albumin having an electrophoretic mobility of 0.19 (hereinafter may be referred also to as “0.19 wheat albumin”) in an amount of 125 mg or more per single diet is believed effective (Non-Patent Document 2). Hitherto, as commercial health foods containing an effective amount of wheat albumin, soup and hard capsules are available on the market. Also, Patent Document 1 discloses a tablet containing 0.19 wheat albumin.